UNIST Reveals Tech to Decompose Nitrous Oxide Efficiently

Abstract

Nitrous oxide (N2O) is one of the top three greenhouse gases, together with carbon dioxide and methane, but it is stable enough not to be easily decomposed under thermocatalytic conditions, even at high temperature (445 °C). Herein, an efficient N2O decomposition method is reported using nickel oxide catalyst under mechanochemical conditions operated near ambient temperature. The mechanochemical N2O decomposition method exhibited a rapid reaction rate of 1761.3 mL h−1 and a high conversion of 99.98% even at 42 °C, compared to the thermochemical method (294.9 mL h−1 and 49.16% at 445 °C). Unlike equilibrium thermocatalytic states, the non-equilibrium mechanocatalytic states induced by intensive dynamic mechanochemical actions are responsible for effective N2O decomposition under mild temperature conditions.

A research team, affiliated with UNIST has announced the development of a novel technology capable of nearly 100% decomposition of nitrous oxide (N₂O) at ambient temperatures. This innovative solution offers a highly energy-efficient way to manage nitrous oxide emissions from engine exhaust and chemical processes, making a significant contribution to greenhouse gas reduction and carbon neutrality efforts.

Professor Jong-Beom Baek and his research team in the School of Energy and Chemical Engineering at UNIST has announced the world's first mechanochemical process that decomposes nitrous oxide using mechanical impacts and friction. This breakthrough was detailed in a research paper published online in Advanced Materials on September 26, with the official publication forthcoming.

N₂O, a gas commonly emitted from chemical manufacturing and engine exhaust, possesses a Global Warming Potential (GWP) approximately 310 times that of carbon dioxide and accelerates ozone layer depletion. Due to its chemical stability, conventional thermal catalytic methods require high temperatures exceeding 445°C to achieve meaningful decomposition, which entails substantial energy consumption.

Figure 1. Schematic representation, illustrating Mechanochemical N2O decomposition.

The research team employed a reaction vessel (ball mill) containing millimeter-sized beads, along with a nickel oxide (NiO) catalyst and nitrous oxide gas. By agitating this setup, the team induced high-energy collisions and friction among the beads, leading to the formation of dense defects and ultra-oxidized states on the NiO catalyst surface. These conditions enable rapid, low-temperature decomposition of N₂O-something previously unachievable with traditional thermal catalysts.

Experimental results demonstrated that this process could decompose nearly 100% of N₂O at just 42°C, achieving a conversion efficiency of 99.98% and an hourly decomposition rate of 1,761 mL. This represents more than a sixfold increase in energy efficiency compared to conventional thermocatalytic methods, which operate at 445°C with a 49.16% conversion rate and an output of 294.9 mL/h.

The team also validated the technology's applicability in real-world scenarios. In tests simulating vehicle diesel engine emissions, the process achieved 95-100% removal of N₂O. Furthermore, in continuous processing setups designed to emulate large-scale gas treatment facilities, an impressive conversion rate of approximately 97.6% was maintained. The technology proved stable even in the presence of oxygen and moisture, typical of actual exhaust gases.

Their findings also revealed that economic analyses indicate that this mechanochemical method is more than eight times more cost-effective than existing thermal catalytic processes.

Professor Baek emphasized, "With the European Union (EU)'s upcoming implementation of the Euro 7 emission standards, which include stricter regulation of nitrous oxide, the importance of effective removal technologies has grown significantly. This innovation can effectively address N₂O emissions from diesel engine exhausts, nitric acid and adipic acid production processes, and ammonia-powered ship engines, thereby supporting carbon neutrality and greenhouse gas reduction efforts."

Journal Reference

Seung-Hyeon Kim, Li-Bo Chen, Jae Seong Lee, et al., "Mechanochemical Nitrous Oxide Decomposition," Adv. Mater., (2025).